<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>伪类选择器</title>
  <style>
    .red{
      width: 100px;
      height: 200px;
      background-color: red;
      transition: width 1s,background 1s;
    }
    .red:hover{
      width: 300px;
      height: 500px;
      background-color: blue;
    }
  /*将字伪装成超链接*/
    span{
      color: blue;
      text-decoration: underline;
      cursor: pointer;
    }
    span:active{
      color: purple;
    }
  </style>
</head>
<body>
<a href="http://taobao.com">淘宝</a>
<span>百度一哈</span>
<div class="red"></div>
</body>
</html>